The controversy still rages over Russia's possible hacking into computer systems used by American political entities. Defense Secretary Ash Carter has warned Russia not to try to interfere with the U.S. general election in November. Yet Republican presidential candidate Donald Trump says he doubts that Russia is involved.

The election -- the heart of U.S. democracy -- is at the center of the debate. But before we tell you how ... a little background.

The system is decentralized. Votes are collected where people live, and then each state sets up its own security, in its own electoral system, to tabulate its votes. This method is intended to reduce fraud.

So imagine the shock when the FBI told Arizona election officials that Russians had hacked into their system. Experts also blame Russia for hacking into Democratic party emails.

A former U.S. ambassador to Georgia and Kazakhstan, William Courtney, writes that Russia will be seen as a "rogue elephant" if it continues its disruptions.

"Great powers have to work with each other to accomplish objectives. So the United States and China are working together on the global warming issue. A great power can't exist in isolation," said Courtney.

Republican presidential nominee Donald Trump told an interviewer on a Russian TV network that he doubts Russia was involved, and Russian President Vladimir Putin denies any connection to the cyberattacks.

Democratic Senator Ben Cardin believes any attacks would have to have been approved by key leaders.

"You have to believe that at the highest levels, that these strategies have been agreed to," said Cardin.

The worry now for Republican Senator Bob Corker is of any Russian tampering in the general election, which will choose the next U.S. president.

"If they can demonstrate that ... maybe they affected it, obviously that creates distrust in the outcome, [and] instability, so that’s a big win for them," said Corker.

Remember the separate state electoral systems? Courtney suggests the Department of Homeland Security should protect election systems as part of the nation's "critical infrastructures."

"That would mean that the U.S. government will be actively involved to encourage those organizations that have good cyber hygiene, to have good anti-virus protections and other things," said Courtney.

But that may be too late to do that for the presidential election, now less than 60 days away.